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    This file is part of the iText (R) project.
    Copyright (c) 1998-2022 iText Group NV
    Authors: iText Software.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License version 3
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    following permission added to Section 15 as permitted in Section 7(a):
    FOR ANY PART OF THE COVERED WORK IN WHICH THE COPYRIGHT IS OWNED BY
    ITEXT GROUP. ITEXT GROUP DISCLAIMS THE WARRANTY OF NON INFRINGEMENT
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    or FITNESS FOR A PARTICULAR PURPOSE.
    See the GNU Affero General Public License for more details.
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 */
using System;
using System.Collections.Generic;
using System.Globalization;
using iTextSharp.tool.xml;
using iTextSharp.tool.xml.css;
namespace iTextSharp.tool.xml.css.apply {

    /**
     * Serves as a container class for the largest font size and/or largest leading found in a tag and all its siblings.
     *
     * @author Emiel Ackermann
     *
     */
    public sealed class MaxLeadingAndSize {
        private CssUtils utils = CssUtils.GetInstance();
        private FontSizeTranslator fontSizeTranslator = FontSizeTranslator.GetInstance();
        private float largestLeading;
        private float largestFont;

        /**
         *
         * @return largest leading
         */
        public float GetLargestLeading() {
            return largestLeading;
        }
        /**
         *
         * @return largest font size
         */
        public float GetLargestFont() {
            return largestFont;
        }
        /**
         * Sets largest font size and largest leading based on the css styles "font-size" and "line-height" of a given tag and its children.
         * @param t tag of which the variables need to be set.
         */
        public void SetVariablesBasedOnChildren(Tag t) {
            float fontSizeParent = fontSizeTranslator.GetFontSize(t);
            float largestFontChildren = GetLargestFontFromChildren(t.Children);
            largestFont = fontSizeParent>largestFontChildren?fontSizeParent:largestFontChildren;
            float leadingParent = CalculateLeading(t);
            float largestLeadingChildren = GetLargestLeadingFromChildren(t.Children);
            largestLeading = leadingParent>largestLeadingChildren?leadingParent:largestLeadingChildren;
        }

        /**
         * Set the largest leading based on calculateLeading only. (Children not taken into account)
         * @param tag the tag
         */
        public void SetLeading(Tag tag) {
            largestLeading = CalculateLeading(tag);
        }
        /**
         * Iterates over all children in a List and returns the largest font size found.
         * @param children IList<Tag> containing a list of children.
         * @return float largest font size.
         */
        public float GetLargestFontFromChildren(IList<Tag> children) {
            float largestFont = 12;
            foreach (Tag tag in children) {
                float fontSize = fontSizeTranslator.GetFontSize(tag);
                if (fontSize > largestFont) {
                    largestFont = fontSize;
                }
            }
            return largestFont;
        }
        /**
         * Iterates over all children in a List and returns the largest leading found.
         * @param children IList<Tag> containing a list of children.
         * @return float largest leading.
         */
        private float GetLargestLeadingFromChildren(IList<Tag> children) {
            float leading = 0;
            foreach (Tag tag in children) {
                float calculatedLineHeight = CalculateLeading(tag);
                if (calculatedLineHeight > leading) {
                    leading = calculatedLineHeight;
                }
                GetLargestLeadingFromChildren(tag.Children);
            }
            return leading;
        }

        /**
         * Calculates the leading of the given tag.
         * <br />
         * First checks which line-height string is present in the css of the tag, if any. Following strings are allowed;
         * <ul>
         * <li>a constant (containing px, in, cm, mm, pc, em, ex or pt),</li>
         * <li>percentage (containing %),</li>
         * <li>multiplier (only digits),</li>
         * </ul>
         * Then this methods calculates the leading based on the font-size and the line-height.<br /><br />
         * If no line-height was given or if the line-height:normal was given, leading = font-size * 1.5f.
         * @param t tag of which the leading has to be calculated.
         * @return float containing the leading of the tag.
         */
        public float CalculateLeading(Tag t) {
            float leading = 0;
            IDictionary<String, String> css = t.CSS;
            float fontSize = fontSizeTranslator.GetFontSize(t);
            if (css.ContainsKey(CSS.Property.LINE_HEIGHT)) {
                String value = css[CSS.Property.LINE_HEIGHT];
                if (utils.IsNumericValue(value)) {
                    leading = float.Parse(value, CultureInfo.InvariantCulture) * fontSize;
                } else if (utils.IsRelativeValue(value)) {
                    leading = utils.ParseRelativeValue(value, fontSize);
                } else if (utils.IsMetricValue(value)){
                    leading = utils.ParsePxInCmMmPcToPt(value);
                }
                // a faulty value was entered for line-height.
                if (leading == 0) {
                    leading = fontSize*1.5f;
                }
            } else {
                leading = fontSize*1.5f;
            }
            return leading;
        }
    }
}
